Sodium Zeolite A is represented by the formula (NaAl SiO.sub.4).sub.12 . 27H.sub.2 O. It has a specific crystalline structure which has been published in numerous references, e.g. U.S. Pat. No. 3,535,075 (issued Oct. 20, 1970). In addition the structure of sodium Zeolite A is described in the book "Molecular Sieve Zeolites - I" - Advances in Chemistry Series, published by the American Chemical Society, Washington, D.C. (1971). FIG. 25 on page 166 of this book provides a pictorial view of the crystal structure of sodium Zeolite A.
Sodium Zeolite A is very useful as a cation exchange resin for calcium and magnesium compounds. This is due to its unusual physical properties.
Many processes are known for preparing sodium Zeolite A. One such process uses kaolin as the alumina source. The kaolin is first calcined and then added to a sodium ion source such as sodium hydroxide or sodium silicate. A silica source (e.g. sodium silicate, water glass, or silica sol) is then added to make the corrent Na:Al:SiO.sub.2 ratio for Zeolite A. This mixture is then heated at 80.degree. to 120.degree. C. for extended periods of time until sodium Zeolite A crystallizes from solution. A disadvantage of this process is that the balance of the clay remains and presents a disposal problem.
My invention provides a novel and improved process for preparing sodium Zeolite A.